Lever operated control switch



Sept, 20, 1949. R.' PRATT LEVER OPERATED CONTROL SWITCH Filed May 4, 1945,

Patented Sept. 20, 1949 2,482,206 LEVER orERATED coNTnoL SWITCH Ryder Pratt, Kirkwood, Mo., assignor, by mesne assignments, to Missouri Automatic Control Corporation, a corporation of Missouri Application May 4, 1945, Serial No. 591,986

Claims.

The present invention relates to a Control switch. More particularly. it relates to a switch construction having high multiplication, mm1- mum lost motion. and rugged construction.

In the drawings:

Fie. 1 is a plan view of the vdev-ite partly broken away;

Fig. 2 isa front-to-rear vertical section on the line 2-v-2 of Fig, 1;

Fig. 3 is a sideeto-side vertical section on the line ,3-3 of Fig. 2;

Fig. 4 is a ver-tical section on .the line 4=4 at the upper middle par-t of Fie. .and

Fis. 5 is a horizontal section on the line 5-5 of Fl 2.

he `switch :includes a more or less U-shaped main supporting base lll, having a top flange Il, a forward panel I2, :and a botto-rn flange '13. 1t has also two short forward side flanges I4 and I5. The two side flanges have ears 16 and I1, respectively, thereon to receive screws ltor attachment purposes, as will appear.

A cover I3 provides 1a. .back panel I9 and two side panels 20 and ZI.. kIt has top and bottom danges so that it may be slipped yover Vthe, opent end of the main supporting ibase I0. Its side panels 20 and 2| overlie vthe short langes I4 and |:5 on the main supporting base. and particularly lie alongside the two vattachmexit ears 1.6 and I1 thereon.

Within the main supporting bese Ill and sem cured adjacent the .liront thereof is anl inner switch housing, generally .indicated at .24, and comprising a front wa11,25,f.a`t0p wall 26., a. bOt'om wall 21, and two side walls 2 8 and .29.. Central projections ofthe bottom and top 'wal-ls .2.6 and 2l are shown at 30 .and 3l. Vthese being designed .to penetrate a front panel 32 of insulating material and to be peened over to hold .the :front panel in lace.

p The side walls 28 .and 29 :liewthin the two ears I6 and I1 on the mainsupvonting base 1,0. `Screws 34 and 35 pass through the side walls 20 and .2l Aof the cover member, athen :through the .ears `I6 and I1, and finally into the side walls .28 and 29 of the inner switch housing. These two screws thereby hold the :several parts together. Additionally, the main supporting .ibase :III has yraiscd portions 36 engageable against the forward surface of the `front -Wall 225 of .the :switch housing member yand registeren-ble :with similar raised portions 31 extending inwardly yfrom that panel y25. A screw `(i8 passes through :both raised Aportions .and k.secures k,these par-ias together in cooperation with vthe ytwo screws .34 nodali.

The operating mechanism includes a thermal device in the form of an outer tube 4U and an inner connecting rod 4t adapted to be joined with an inner tube portion, all as shown in co-pending application Serial No. 588,554, filed April 16, 1945, for Heat-responsive element, by this inventor. The inner end of the rod 4I receives a headed screw 42 for threaded adjustment thereinto. It will be understood that upon being subjected to great changes in heat conditions within a stach or the like the tube 40 will expand to a greater extent than the inner member including the rod 4i, and will draw the screw 42 to the right. Similarly, upon cooling, the screw 42 will be moved to the left.

A primary lever 43 is pivoted at 44 to the side walls 2.8 and 29 of the inner switch housing. The pivot 44 consists of a rod that extends all the way through the flanges on the primary lever 43 to the aforesaid side walls 28 and 29, as appears in the upper part of Fig. 3.

The primary lever is cut away in its middle portion and surrounds the screw 42. At points beginning slightly above the two screws 34 and ,35, the primary lever is cut inwardly to a. narrow lower part. Riveted to this narrow lower part is an additional member 45 that projects back into the opening, whereby the primary lever straddles the screw 42. This member 45 has backwardly struck forked ends 46 that engage the forward side `of the head of the screw 42. As a, consequence, it will be seen that, when the head o f the screw is moved to the right in Fig. v2, if Will pivot the primary lever 43 counterclockwise about the pivot 44. The member 45 is resilient, to absorb any overtravel of the heat-responsive element.

The lower end of the primary lever 43 is turned backwardly to receive one end of a. bronze pivot spring 41, the other end vof which is attached to the turned baci: end of a secondary lever member 48. The secondary lever is mounted pivotally on a pivot rod 49 that passes through ears outstruck from the sides of the secondary lever 48 and passing through the flanges 28 and 29 of the switch housing. It may thus be seen that the secondary lever is caused to pivot clockwise about its pivot 49 upon clockwise pivoting of the primary lever 43 about its pivot 44.

The secondary lever 48 has an arm of insulating ymaterial 50 extending upwardly therefrom. The upwardly extending secondary `lever thereby lies alongside the primary lever 43. Owing to the differences in the leverages of the two levers, it may be seen that the upperend of the secondary lever 50 will vhave ahighly multiplied movement.

A spring blade 52 is secured rigidly to a terminal 53 that extends through the panel 32 of the switch housing. This spring blade 52 is bent in the manner shown in Fig. 2, and normally exerts a force to the right in Fig. 2. At its upper end, it contains a switch contact element 54, the back of which is urged against the upper end of the secondary lever 50 by the inherent resiliency of the spring blade 52. This force exerted against the secondary lever tends to pivot that lever clockwise about its pivot 49.

The terminal 53 includes a screw 55 by which a proper electrical lead may be brought thereto and may be put into contact with the switch blade 52. It will be seen that this blade is otherwise insulated because of the insulated character of the panel 32 of the switch housing.

Upwardly on the switch housing from the terminal 53 is another terminal 51 which has a screw 58 for attachment of an electrical wire. The terminal projects through a terminal plate 59 within the switch housing and secures the terminal plate against the inner face of the housing. This plate 59 has an upper head portion projecting through the iront panel 32 of the switch housing, and this head portion receives an adjustable contact member 60. This contact member is disposed opposite the contact member 54 on the spring blade 52 and is adjustable toward and from this contact. A protective cap 6I is secured to the switch housing panel 32 to prevent accidental displacement of the contact 60 after it is once adjusted. It will further be observed that accidental displacement is prevented by the fact that the plate 59 is slit at its upper end (as shown in Figs. 2 and 4) so that it is normally urged inwardly, the two bifurcations being spread by the presence of the screw 60.

Operation When the stach unit 4B is cold, the screw 42 will be displaced to the left, permitting maximum clockwise movement of the primary lever 43 about its pivot 44. This maximum movement is effected by the action of the spring switch blade 52 against the upper end 5@ of the secondary lever 48, pivoting that lever the maximum distance clockwise about its pivot 49. When it so moves, it acts through the bronze spring 4l to draw the lower end of the primary lever 43 leftward as far as is permitted. The distance of such movement is determined by the engagement of the prongs 46 against the lower end of the head of the screw 42.

When the screw 52 moves to the right under the iniiuence of a heated stack member, it acts against the prongs 46 and moves them to the right in Fig. 2, thereby pivoting the primary lever 43 counterclockwise about the pivot 44. This movement is transmitted to the secondary lever through the bronze spring 41, drawing the end of the secondary lever below the pivot 49 to the right, and thereby pivoting the upper end 50 to the left, against the influence o the spring blade switch 52. When this movement proceeds to a desired point, the contact member 54 on the spring switch blade will engage electrically with the iixed contact B0, thereby completing the circuit. The particular temperature conditions of the stack unit required to effect closure of the two contacts may be adjusted by adjusting the screw 60 toward or from the contact 54.

It will be seen that the switch hereinbefore described provides a mechanism that is relatively simple in construction which provides a large multiplication of forces with a minimum number of parts, all assembled in a highly compact arrangement. (Note that the member 45 will permit overtravel of the screw head 42 to the right.)

What is claimed is:

1. In a switch mechanism, a housing, a rst lever pivoted on the housing, a force element adapted to apply force to move the first lever in one direction, said rst lever having resilient prong means adapted to be abutted by the force element for transmission of the movement from the force element to the rst lever, the resiliency of said prong means permitting overtravel of said force element without further movement of said first lever after a predetermined maximum movement of said first lever, a second lever lying alongside the iirst lever and connected therewith for movement thereby, said second lever being pivoted to the housing adjacent its connection aforesaid, and extending beyond the pivot, a spring switch contact blade secured to the housing and extending adjacent the extending end of the second lever, said blade normally engaging the second lever and urging it oppositely to the direction applied by the force element and the second lever, and a second contact engageable by the contact blade.

2. In a switch mechanism, a housing, a first lever pivoted on the housing, a force element adapted to apply force to move the rst lever in one direction, said rst lever having resilient prong means adapted to be abutted by the force element for transmission of the movement from the force element to the first lever, the resiliency of said prong means permitting overtravel of said force element without further movement of said rst lever after a predetermined maximum movement of said rst lever, a second lever lying alongside the rst lever and connected therewith for movement thereby, said second lever being `pivoted to the housing adjacent its connection aforesaid, and extending beyond the pivot, a spring switch contact blade secured to the housing and extending adjacent the extending end of the second lever, said blade normally engaging the second lever and urging it oppositely to the direction applied by the force element and the second lever, and a second contact engageable by the contact blade, said blade being fixed at its end opposite the second contact to the housing and having an electrical terminal.

3. In a switch mechanism, a housing, a first lever pivoted on the housing, a force element adapted to apply force to move the rst lever in one direction, said rst lever having resilient prong means adapted to be abutted by the force element for transmission of the movement from the force element to the rst lever, the resiliency of said prong means permitting overtravel of said force element without further movement of said iirst lever after a predetermined maximum movement of said first lever, a second lever lying alongside the Iirst lever and a spring blade pivot by which it is connected therewith for movement thereby, said second lever being pivoted to the housing adjacent its connection aforesaid, and having an electrically insulative portion extending beyond the pivot, a spring switch contact blade secured to the housing and extending adjacent the extending end of the second lever, said blade normally engaging the second lever and urging it oppositely to the direction applied bythe force element and the second lever, and a second contact engageable by the contact blade.

4. In a switch mechanism, a housing, an oppositely movable power driven element on the housing, a rst lever pivoted at its rst end to the housing, the end being at one side of the power element, the lever extending across the power element to dispose its second end 0n the other side thereof, a resilient member secured to said rst lever and in contact with said power element for transmission of movement of said power element to said rst lever, said resilient member permitting overtravel of said element without further movement of or damage to said first lever after said first lever has pivoted a predetermined maximum degree, a second lever alongside the first, the second lever being connected to the second end of the first lever to be moved thereby, pivoted to the housing, and having a free end extending beyond said pivot, a spring switch blade having a rst contact thereon, the blade being mounted on the housing, extending along the free end of the second lever, the blade f ber, and the head being hookable over the said resilient member to move it and said rst lever in one direction against the force of the spring blade.

5. In a switch mechanism, a housing, a power moved element extending into the housing, a first lever pivotally mounted in said housing including a resilient member contacting said element for transmission of movement of said element to said first lever, said resilient member permitting overtravel of said element without further movement of or damage to said rst lever after said iirst lever has pivoted a predetermined maximum degree, a second lever pivotally mounted in said housing and having a free end, said rst lever being connected to said second lever close to the pivot point of the latter for pull-pivoting thereof upon pivotal movement cf said rst lever, movement of the free end of said second lever being thereby multiplied a predetermined number of times the movement of said element, a resilient switch blade having a free end engaging the free end of said second lever and biasing it against movement by said rst lever, a contact on said blade, and a second contact, said blade Contact being movable into engagement with said second contact through pivotal movement of said second lever.

RYDER PRATT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 690,445 Leadbeater Jan. '7, 1902 1,732,182 Denison Oct. 15, 1929 1,903,924 Irwin Apr. 18, 1933 2,225,236 Shaw Dec. 17, 1940 FOREIGN PATENTS Number Country Date 599,846 Germany July 10, 1934 603,795 Germany Oct. 8, 1934 

